Zend does not have any official recommendations for what should be replicated to the DR machine in a high availability setting. Replication settings are the responsibility of the customer. However, here are some tips from Zend Support that may be helpful.
Zend Server for IBM i, any version, running on any supported version of IBM i
Before starting replication for the first time, install all of the Licensed Programs and PTFs at the same level as they are installed on the current machine. In particular, install the same version of Zend Server and any Hotfixes or Updates as are on the production server, and install the license. Please note that when you add a DR machine, you do need to obtain licensing for it from Zend. Contact your Zend Account Manager for more information. If you do not know your Account Manager, you can contact Zend Support or use the chat feature at zend.com to get a message to your Account Manager.
Please replicate the ZENDSVR6 library (or ZENDSVR library if still on version 5)
Please replicate these folders and all their subfolders in the IFS:
/usr/local/zendphp7 (/usr/local/zendsvr6 for versions 6-8)
/www/zendphp7 (/www/zendsvr6 for versions 6-8)
If you have any additional folders where you keep your scripts and other web content, or if you have any additional Apache instances configured to use PHP, you should replicate those folders as well.
Some products like Mimix rely on journaling the IFS folders to perform replication. You should never journal this folder:
/usr/local/zendphp7/tmp (/usr/local/zendsvr6/tmp for versions 6-8)
This folder contains shared memory objects and other IPC objects that do not function correctly when journaled. Never journal this folder. Instead, do not replicate it, and do not leave Zend Server up and running on the DR box. In the event of a failover, start Zend Server on the failover box using the reset option on the menu. This will clear the shared memory and start fresh: